// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_
#define UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_

#include "base/time/time.h"
#include "ui/compositor/compositor_export.h"

namespace ui {

class Compositor;

// A compositor observer is notified when compositing completes.
class COMPOSITOR_EXPORT CompositorObserver {
public:
    // A commit proxies information from the main thread to the compositor
    // thread. It typically happens when some state changes that will require a
    // composite. In the multi-threaded case, many commits may happen between
    // two successive composites. In the single-threaded, a single commit
    // between two composites (just before the composite as part of the
    // composite cycle). If the compositor is locked, it will not send this
    // this signal.
    virtual void OnCompositingDidCommit(Compositor* compositor) = 0;

    // Called when compositing started: it has taken all the layer changes into
    // account and has issued the graphics commands.
    virtual void OnCompositingStarted(Compositor* compositor,
        base::TimeTicks start_time)
        = 0;

    // Called when compositing completes: the present to screen has completed.
    virtual void OnCompositingEnded(Compositor* compositor) = 0;

    // Called when compositing is aborted (e.g. lost graphics context).
    virtual void OnCompositingAborted(Compositor* compositor) = 0;

    // Called when the compositor lock state changes.
    virtual void OnCompositingLockStateChanged(Compositor* compositor) = 0;

    // Called at the top of the compositor's destructor, to give observers a
    // chance to remove themselves.
    virtual void OnCompositingShuttingDown(Compositor* compositor) = 0;
};

} // namespace ui

#endif // UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_
